When a person wishes to radically change the color of his or her hair, such as when he or she wishes to obtain a color lighter than his or her original color, it is often necessary to bleach and, where necessary, to dye the hair. Several methods exist for doing this.
The first method consists in using lightening products based on aqueous ammonia and hydrogen peroxide. These products may optionally contain dyes, which allow the hair to be lightened and simultaneously dyed. However, the lightening performance of these products remains limited, more particularly for applications to natural and/or dyed dark foundation colors.
The second method consists in applying to the hair a lightening composition based on peroxygenated salts such as persulfate and alkaline agents to which has been added hydrogen peroxide at the time of use, in order to obtain greater lightening. This type of product can be satisfactory and suited to dark foundation color, but may lead to only a restricted range of tints. It thus may be necessary to correct the shade obtained by applying, in a second stage, a dye product to the hair. This two-step process has the drawback of being relatively long.
To overcome this drawback, it is known practice to add dyes to these lightening products. This method can allow the hair fiber to be dyed and simultaneously bleached. Since the level of lightening is substantial, it may be suited to natural and/or dyed foundation colors. However, there is a limited number of dyes that are stable under these highly oxidative conditions, which limits the variety of tints that may be obtained. Moreover, this instability may be reflected by a more or less rapid change in the tint during application, which may lead to inconsistent results.
Moreover, the color-fastness of these dyes with respect to external agents, such as light and shampoo, may not be satisfactory.
Direct dyes of anthraquinone, azo, triarylmethane, thiazine, quinone and nitro type, which are stable in these highly oxidative media, have been proposed in U.S. Pat. No. 5,688,291, International Patent Application Publication No. WO 02/074 270, and German Patent No. DE 203 03 559. However, these dyes are unsatisfactory in terms of chromaticity, color-fastness and stability during the application time.
Thus, there is a need in the art for novel compositions for bleaching and simultaneously dyeing keratin fibers, such as human keratin fibers including the hair, which are particularly suitable for dark foundation colors, which show good stability over time and which allow chromatic and color-fast colorations to be obtained.